Performance of fixed‐gain amplify‐and‐forward nonlinear relaying with hardware impairments

Summary In this paper, a fixed-gain amplify-and-forward relaying under non-ideal hardware is analyzed. The relaying system is impaired because of relay's power amplifier (PA) nonlinearity and in-phase and quadrature-phase (IQ) imbalance at a destination. Closed-form expressions for outage probability as well as ergodic capacity approximation and its upper bound are derived. Also, the outage probability and the ergodic capacity asymptotic expressions in the high signal-to-noise ratio are deduced. For the first time, the joint influence of PA nonlinearity and IQ imbalance on the system in terms of outage probability, symbol error rate, and ergodic capacity is investigated. The results are compared with the respect to soft envelope limiter and traveling-wave tube amplifier at the relay. Based on the analytical and the numerical results, important insights into the impact of IQ imbalance and nonlinearity of the aforementioned PA models on the system performance are gained as well as valuable information on the performance of practically deployed fixed-gain amplify-and-forward relaying system. Copyright © 2015 John Wiley & Sons, Ltd.